News | May 14, 1999

Turnkey Packaging House Preps Plastic Chip Carriers

If you're designing-in ASICs or other high-density ICs, and you're seeking the smallest possible form-factor chip carriers, locating a packaging vendor that can support your effort should be a significant part of your design strategy. A company to know about, whose motto might be "Good things come in small packages," is ASAT (Fremont, CA; formerly known as Advanced Semiconductor Assembly Technology).

As a multinational semiconductor assembly contractor, ASAT is a company at the leading edge in IC packaging for both high-speed and space conserving designs. ASAT's expertise spans a number of phases of the packaging effort, including design, assembly, and test--for digital, mixed-signal, and analog ICs. It's also an expert on chip-scale packaging (CSP), and has alliances with a number of shakers and movers in the CSP revolution.

Put It In Plastic

Click here to see Figure 1.

ASAT's latest "near chip-scale package" is an advanced Leadless Plastic Chip Carrier (LPCC) product the company believes will change the look and feel of compact circuit boards forever.

Moreover, ASAT's LPCC thrust extends a line of existing product offerings that rely on using pre-existing equipment from the firm's leaded package and ball grid array (BGA) product lines. "One key to the LPCC is a generic net-list that permits a variety of ICs to mount into the package immediately," notes Ed Combs, ASAT's executive vice president of customer engineering. "That can be done without design modifications to the package's etched copper leadframe."

Click here to see Figure 2.

Can You Get It Yesterday?

In addition to flexibility of new design, Combs says the LPCC can be delivered with an unheard of ten day lead time--and that includes design of the leadframe! This can help you shorten manufacturing cycle times considerably.

The new LPCC has several advantages over other types of IC packaging too. When soldered down, the package's die-attach paddle makes contact with the underlying substrates, providing enhanced thermal--and electrical--performance.

Slashing Parasitics

Click here to see Figure 3.

A comparison of thermal resistances to QFPs shows significant reductions in thermal resistance. Similarly, a comparison of lead inductance (both mutual- and self-inductance) reveals very low values--a feature that can help you match impedances of transmission line I/Os.

Significantly, the ASAT LPCC, with lead pitches as small as 0.4 mm (16 mils), permits the use of your existing SMT infrastructure, placement machines, and processes. ASAT is offering its LPCCs in body sizes ranging from four mm x four mm to nine mm x nine mm, with I/O lead counts between 16 and 48.

"The LPCC is a new concept and something everybody is looking at as a Level One package," notes Dick Brancato, the firm's president. "LPCC, as a near CSP, it delivers performance electrically and thermally. For that reason, it's being looked at very closely and enthusiastically by people doing things such as handheld and cellphone design. OEMs like it because it's a very price-competitive alternative to lower pin-count BGAs."

Presented to JEDEC

ASAT's patent pending LPCC design--now in beta testing--is also being presented to JEDEC for approval as an industry standard. This effort is in conjunction with packaging house Amkor Technology. "LPCC is promising as a high volume alternative, especially for jellybean devices," asserts Combs.

Combs also points to the package's light weight, high I/O, and ground bonding to die pad capability. He also touts the LPCC's ease of test and low z-height of 0.8 mm. Combs also emphasizes that ASAT can deliver LPCC product in whatever form an OEM could want for manufacturing runs, including trays, tubes, and tape-and-reel put-ups.

Cheap BGAs

If you need higher I/O capacity than what today's LPCCs can offer, ASAT is also gearing up its FxBGA flex-BGA product line. Its flex-BGA is a low profile (typically one mm) package that can accommodate up to 180 signal lines in a 12 mm x 12 mm footprint. Like the LPCC, FxBGA packages are low cost, thanks to an inexpensive flexible polyimide substrate and an overmolded covering. The FxBGA also offers high routing density and short electrical paths. Like the LPCC, it lends itself to your existing SMT infrastructure.

For more details on these developments, contact Dick Brancato, Ed Combs, or Bill Burks at ASAT Inc., 46335 Landing Parkway, Fremont, CA 94538. Phone: (510) 249-1222. Fax: (510) 249-9105.